This invention relates to a guidance system for towed vehicles and more particularly to an automatic guidance system for a towed farm implement.
The increase of the average farm size has resulted in the use of larger farm equipment. The guidance of this wider equipment while in the field can have considerable effect upon the machine's effective field capacity and thus its field efficiency. Some agricultural operations require extreme guidance accuracy due to various reasons. A common example concerns applications of herbicide. If two "passes" lap over one another possible damage to the crop may result, while if a strip is completely missed, no weed control will be present. Row crop planters also require a high degree of accurate guidance for efficient operation. The markers on a 24 row planter with a 30 inch row spacing are in the vicinity of 30 feet in length. These markers often require one joint to enable the marker to fold, and sometimes two such joints are used. Markers of such length are cumbersome and unwieldy to maneuver.
Many methods of guidance have been utilized and have been generally directed to the guidance of the tractor rather than the guidance of the towed implement. One method involved an operator at a remote location in the field and controlling the tractor by radio control. Another method comprised infrared detectors positioned at the ends of the field which would locate the machine's position by referencing to hot tractor gases. Still other methods involve an electric cable buried in a field with a magnetic follower able to follow the cable down the field, and the utilization of light, radar or infrared beams in which the machine would run between two of these sending units. All of these systems were costly and involved numerous pieces of complex mechanical and electrical sensors and mechanisms. Also to control the location of the towed implement by guidance of the tractor is cumbersome, inaccurate and not as responsive as guidance of the towed implement alone.
Previous guidance systems were not versatile to allow the farmer to use various sizes of equipment for planting, cultivating and harvesting and lacked spacing accuracy to enable exact placement of rows year after year to fully utilize any fertilizer or herbicide that may be banded.